text:
Within the US: When, and by whom, is the Transition Level determined/published?
There are several SE Q&As that deal with the terms Transition Altitude, Transition Layer, and Transition Level.  The very-brief, paraphrased definition of the Transition Level (TL) is:

The lowest usable flight level that can be assigned, and the point at which aircraft descending out of the flight levels will change their altimeters back to QNH.

Due to atmospheric pressure variations, the TL can vary from day to day and (maybe?) region to region.
My five questions about the Transition Level are thus:

Is the entire US using the same TL at any given point in time?
Or, are individual ARTCCs setting their own TL based on the lowest QNH reading in their geographical area?
Or, are individual sectors within an ARTCC setting their own TL based on the lowest QNH reading in their even-smaller geographical area?

If the individual sector controllers are NOT making the determination "on the fly", I then assume that the TL is determined by a "higher authority" and published to all controllers/sectors/centers under that authority. Which leads to the fourth and fifth questions:

Who (what level, position, etc.) determines the TL?
When, or how often, is this determination made?


text:
Equations for Computing Temperature and Air Density Ratios at Different Altitudes
When computing aircraft performance at different altitudes, two useful variables are the air density ratio (dr) and temperature (T). Using a ratio is helpful because you can recompute values, such as dynamic pressure (Q), by simply multiplying the seal level value by the ratio. And regardless of what units you are using to represent air density, you can compute that value by multiplying the sea level value of that unit by the ratio.
The International Standard Atmosphere (ISA) tables contain standard values for these variables at different heights (h), stated in both meters and feet. These tables have been adopted by the International Civil Aviation Organization (ICAO) and can be found in ICAO Doc 7488/3. The US Standard Atmosphere is essentially identical.
Are there simple equations that I can use in an Excel spreadsheet to compute the air density ratio and temperature in SI units and US units that will agree with the ISA tables?

Yes, there are equations that can provide you with values that agree with the values in the ISA tables down to the nearest 100,000th (five digits), using the Geopotential altitudes.
Different equations apply to the Troposphere, which extends from Sea Level up to 11,000 meters (36,089 feet rounded), the Tropopause, which extents up to 20,000 meters (65,617 feet rounded) and the portion of the Stratosphere up to 30,000 meters (98,425 feet rounded). This is well above the altitude at which wings lose effectiveness.
Since the pressure ratio is related to the density ratio and the temperature ratio and since the temperature ratio is easily computed, I am adding computations for the temperature ratio and the pressure ratio.
The equations are described using Excel operators, such as * for multiplication and ^ for exponentiation, and Excel functions, such as EXP for e raised to the specified power. The units are described standard notations, such as ft for feet, m for meters, s for second and kg for kilogram. The notations do not use superscript, so that meters squared is m2, etc.  I am using P for pressure, p for density, Tr for temperature ratio, pr for density ratio, Pr for pressure ratio and L for lapse rate.
1. TEMPERATURE AND TEMPERATURE RATIO
The equations for computing standard temperature are fairly simple and the results agree with the tables exactly. The temperature ratio can be computed by computing the Kelvin temperature and dividing the result by 288.15K. Thus, we will include the equations for computing T(K) in US units.
a. Troposphere
In the Troposphere, the basic equation is:
T = T0 - L * h
Where T0 is the temperature at sea level, L is the lapse rate and h is the height.
In SI units, T0 is 15 degrees Centigrade (15C) or 288.15 degrees Kelvin (288.15K), X is .0065 and h is in meters. The equations are:
T(C) = 15(C) - (0.0065(C) * h(m))
T(K) = 288.15(K) - (0.0065(K) * h(m))
In US units, T0 is 59 degrees Fahrenheit (59F), X is .00356616F and h is in feet. The equation is:
T(F) = 59(F) - (0.00356616(F) * h(ft))
T(K) = 288.15(K) - (0.0.0019812(K) * h(f))
b. Tropopause
In the Tropopause, the temperatures  are constant.
In SI units:
T(C) = -56.5C
TK) = 216.65K
In US units:
T(F) = -69.7F
TK) = 216.65K
c. Stratosphere
In the Stratosphere, the temperature increases with height. The basic equation is:
T = T20 + L * (h - h20)
where T20 is the base temperature, L is the lapse rate and h20 is the base height.
In SI units, T20 is -56.5C or 216.65K, X is 0.001, h0 is 20000 meters. The equations are:
T(C) = -56.5(C) + (0.001(C) * (h(m) - 20000))
T(K) = 216.65(K) + (0.001(K) * (h(m)) - 20000))
which can be simplified to:
T(C) = -76.5(C) + (0.001(C) * h(m))
T(K) = 196.65(K) + (0.001(K) * (h(ft))
In US units, T20 is -67.7F, X is 0.00054864 and h0 is 65,617 feet. The equations are:
T(F) = -69.7F + 0.00054864 *(h(ft) - 65617)
T(K) = 216.65(K) + (0.0003048(K) * (h(m)) - 65617))
which can be shortened to:
T(F) = -105.7F + 0.00054864 * h(ft)
T(K) = 196.65(K) + (0.0003048(K) * (h(ft))
2. DENSITY RATIO
The equations for computing standard Density ratio are more complex, but the results (with added improvements) agree with the tables to the nearest .00001.
a. Troposphere
In the Troposphere, the basic form of the equation is the same in SI and US units:
pr = a ^ b
where A is the temperature index (in Kelvins) and the exponent b equals 4.2561.
Where height is measured in meters, standard the equation is:
pr = (1 - (0.0065 * h(m) / 288.15)) ^ 4.2561
You can improve the results by changing the exponent as follows:
d = (1 - (0.0065 * h(m) / 288.15)) ^ 4.25587971
Where height is measured in feet, the standard equation is:
pr = (1 - (h(ft) * 0.0019812/288.15)) ^ 4.2561
You can improve the results by changing the exponent as follows:
pr = (1 - (h(ft) * 0.0019812/288.15)) ^ 4.255882
b. Tropopause
In the Tropopause, the basic equation is:
pr = dr11 / exp((h - h11) * g / (R * T11))
where dr11 is the density ratio at the start of the Tropopause (.297076), h11 is the base height, g is gravitational acceleration, R is the specific gas constant for dry air and T11 is the base temperature (216.65K). Since g, R and T11 are constant, they can be combined into a single constant (X). The revised equation is:
pr = .297076 / exp(X * (h - h11))
In SI units, g is 9.80665 ft.s2, R is 287.05287 m2/s2 and h11 is 11,000 meters. Thus, X is 0.000157689. The equation is:
pr = .297076 / exp(0.000157689 * (h(m) - 20,000))
which can be shortened to:
pr = .297076 / exp(0.000157689 * h(m) - 1.734579))
In US unites, g is 32.1740486, R is 3089.8113775 ft2/s2 and h11 is 36,089 feet. Thus X is 0.000048063. The equation is:
pr = .297076 / exp(0.000048063 * (h(ft) - 36,089))
which can be shortened to:
pr = .297076 / exp(0.00004806346 * h(ft) - 1.734546))
c. Stratosphere
In the Stratosphere, we must first compute the Kelvin temperature first.
In SI units, the equation  is:
T(K) = 196.65(K) + (0.001(K) * (h(m))
In US units, the equation is:
T(K) = 196.65(K) + (0.0003048(K) * (h(ft))
The basic equation for computing density altitude is:
pr = (P20/(p0RT(K)*(T(K)/216.65)^34.1632))
where P20 is the base air pressure, p0 is the air density at Sea Level and R is the specific gas constant for dry air. Since these are constants, they can be combined into a single value (X). The modified equation is:
pr = (X / (T(K) * (T(K) / 216.65) ^ 34.1632))
In SI units, P20 is 5474.9 N/m2, p0 is 1.225 kg/m3, and R is 287.05287 m2/s2. In US units, P20 is 114.345664 lb/ft2, p0 is0.0023769 slgs/ft3, and R is 3089.8113775 ft2/s2. Thus, in both cases, X is 15.569627, which means that we can use the same equation for both SI and US purposes:
pr = (15.569627/(T(K)*(T(K)/216.65)^34.1632))
3. PRESSURE RATIO
The equation for computing the pressure ratio is:
Pr= Tr*pr.
The equation for computing the temperature ratio is:
Tr=T(K)/288.15
We have included equations for computing T(K) in both SI and US units. Once you have the temperature ratio, you can use the density ratio and the formula above to compute the pressure ratio in both SI and US units.
RECAP
SI Units
Troposphere (0 meters to 11,000 meters):
T(C) = 15(C) - (0.0065(C) * h(m))
T(K) = 288.15(K) - (0.0065(K) * h(m))
pr = (1-(0.0065*h(m)/288.15))^4.25587971
Tropopause (11,000 meters to 20,000 meters):
T(C) = -56.5C
T(K) = 216.65K
pr = .297076/exp(0.000157689*h-1.734579)):
Stratosphere (20,000 meters to 30,000 meters)
T(C) = -76.5(C) + (0.001(C) * h(m))
T(K) = 196.65(K) + (0.001(K) * (h(m))
pr = (15.569627/(T(K)*(T(K)/216.65)^34.1632))
US Units
Troposphere (0 feet to 36,089 feet):
T(F) = 59(F) - (0.00356616(F) * h(ft))
pr = (1-(h(ft)*0.0019812/288.15))^4.255882
Tropopause (36,089 feet to 65,617 feet):
T(F) = -69.7F
T(K) = 216.65K
pr = .297076/exp(0.00004806346*h(ft)-1.734546))
Stratosphere (65,617 feet to 98,425 feet):
T(F) = -105.7F + 0.00054864 * h(ft)
T(K) = 196.65(K) + (0.0003048(K) * (h(ft))
pr = (15.569627/(T(K)*(T(K)/216.65)^34.1632))
SOURCE DOCUMENTS
Here are links to the ISA Tables and the Excel workbooks that I used to test these equations.

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text:
What is the ferry range of an A380?
The Wikipedia entry for the A380 gives the maximum range at design load as 15,700 km. The equivalent entry for a Boeing 747-400 gives around 14,000 km but distances of 18,000 km have been performed in demonstrations. So I infer the ferry range for the A380 would be even higher.
Is it specified anywhere? Has a flight by an A380 in excess of 15,700 km been performed to date? Could it fly between any two suitable airports on Earth, i.e., farther than 20,038 km?

When going for a long haul flight and you don't need to deliver a payload other than the plain you can install extra fuel tanks for extra range.

A lovely interactive map shows that only New Zealand is out of range of a normally-laden non-stop A380 flight starting in Europe. Perhaps an A380 with no passengers, no luggage and no cargo can manage the few extra km.

@RedGrittyBrick Remember that Russia west of the Urals is in Europe.  A range of 15,700km around Samara just includes New Zealand.

@David: Yes I should have written Toulouse rather than Europe. That's where Airbus would start any ferrying.

Adding extra fuel tanks might be useful for a 717 but the question is would it be necessary for an unladen A380?

For going between "basically any two airports on earth", I think that the 777-200LR is probably the most able

@Markasoftware: but the Q is specifically about the A380 not about the GlobalFlyer or other long-range aircraft.

Be aware that Boeing has used special high energy fuel to make very long ferry flights non-stop.  Presumably this fuel is also available to Airbus.  The question should specify "regular" or "high test" fuel when considering range.

Short answer to "Can it fly between any two airports on earth?":  No, it can not.  Mainly because it can not takeoff from or land at many smaller airports due to runway length and/or obstacles.

@Lnafziger though the question is vague pls assume he means "any two suitable airports". You cannot hope for A380 to take off from some beach airport in carribean and land on aircraft carrier.

@vasin1987 "Suitable" is a bit problematic though because there are many airports that can be used by the A380 (and therefore suitable) but could not be used when taking off for a maximum range flight.  Using only airports that they could use for this purpose would severely limit the choices.

Q: Could it fly between any two suitable airports on Earth, i.e. further than 20038km?
A: Not likely

It would be better if you interpreted the images with your own words as well.

You could probably stretch out the range beyond what is shown on the chart by adding ferry tanks but I doubt it would make any commercial sense to do so. Designing and fitting the ferry tanks would likely cost far more than adding some fuel stops.

Also what's the source of the image?

You have asked several questions. I'll try to answer them in order to clarify.
Is the ferry range specified anywhere?
From the Airbus website, we find for the Engine Alliance GP7000 engine option the ferry range is ~9,600 NM. Let's just say it's 9,500 NM.
A: 9,500 NM. Also, waiting for the right trade winds can increase you range.

Can an A380 fly between any two airports on Earth?
If you place the originating marker over Dubai, UAE, then the A380-800 can fly to any airport on Earth except a region in South Pacific Ocean. This area (a circle of around 6500 km diameter) has many small island states (French Polynesia, Cook Island, American Samoa etc.).
(gcmap.com)
A: Yes, probably over 99% of airports.

Has a flight by an A380 in excess of 15,700 km been performed to date?
None that I could find. The longest flight of A380 (currently) is QF 8 (with duration 16:50 hours).
We know that A380 (October 25, 20071) is much newer than 777 (June 7, 19952) and 747 (January 22, 19703). In future, there can be attempts to fly it in excess of 15,700 km.
A: No record so far.

What is the ferry range of an A380?
This was your original question. Most of the flights mentioned on the Wikipedia article you referred to were either delivery flights or for demonstration purposes. For such flights, you can have:

lesser people on board
lesser equipment (seats etc.) so more space to add extra fuel tanks

With the above two changes, the result would be:

Less people = Less weight. The aircraft will weigh less and its range can increase.
Less seats = Less weight. The aircraft will weigh less and its range can increase.
More space to add fuel tanks. The aircraft's range will increase.

In addition, A380-800 has cargo volume of 6500 cubic feet. If we have a hypothetical rubber tank which fills all this space, we can add 184,000+ L of additional fuel than the original capacity of 323,546 L. This can increase the range over 50%.
This website contains pictures of additional fuel tanks. As you can see, those are inflatable and can adjust to the space available.
A: It depends.

1: Introduction with Singapore Airlines
2: Introduction with United Airlines
3: Introduction with Pan American World Airways

This is a really comprehensive and well analysed answer, +1.

However, I believe most commercial airplanes would use something more robust than rubber fuel tanks. And all the airplanes on that site are at the most twin-turboprop engines. I guess rubber tanks aren't too good at managing the high fuel burn rates of massive turbofans like those on the A380.
See this picture of fuel tanks loaded up on a Boeing 717: http://cdn-www.airliners.net/aviation-photos/photos/4/8/8/0148884.jpg

@shortstheory I mentioned rubber tanks hypothetically to fill up all cargo space. Your picture is nice.

You've not answered the "any two airports" question, as your post implies a required stopover at UAE...

@Federico First of all, that was a hypothetical situation. If we somehow add fuel to all of the available 6500 cubic feet, it increase fuel capacity to 56.88%. Yes, the fuel weight increases aircraft weight, but at the same time we don't have any cargo weight either.

@JonStory No, it does not imply a stopover at UAE. I said that it will originate from UAE.

Q: Can an A380 fly between any two airports on Earth? But your answer only proves that an aircraft can get to 99% of airports from UAE, not from any other airport.

Oh, you're right, I did not considered that. By using the MTOW as initial weight and your fuel numbers, you get a range increase of almost 80%

If you start with the empty weight and fill it to MTOW with fuel, you only get about 12.8% more fuel than the max capacity. At least that's what I calculated.

I agree with @fooot: just because you can fill the extra space with the same volume of fuel does not mean those fuel will have the same weight as the cargo.

@JonStory OP asked that if A380 can fly between any two airports? I had to place the originating marker at some place where the vast majority of airports of the world can be reached. Of course A380 cannot circumnavigate without refueling. Not all areas of the world have the same number of airports per 100 square miles. That was the reason I placed the marker at UAE as from there, most of Earth's land area is covered and hence most of Earth's airports are covered. I hope this clarifies your question.

But that doesn't mean the A380 can fly from anywhere in the radius you showed, to anywhere else. You can fly UAE to 99%, sure, but start placing the starting point in LESS optimal positions and you realise that there are a LOT of airports pairs that don't work. You've chosen an optimal airport which makes it look better than it is. The A380 can probably only fly between something like 80% of airport pairs, over the whole globe

@JonStory Stack Exchange comments are not supposed to be used to carry on chat, that is what chat is for. If you feel Farhan's answer is in error, please make your own answer.

This answer, while well-researched, does not provide an answer to the question. I appreciate that an answer might not be easily accessible (or even published), but I can't accept an answer that doesn't have it. Also, "between any two airports" isn't the same as "between a particular airport and any other"; and the webmaster email isn't particularly helpful.

It cannot fly between any two airports for a simple reason. Any departure from an airport that is located above 2,000m (e.g. Addis Ababa) would reduce the range due to lower fuel capacity in the tanks.

Could you expand on your answer a little? I'm wondering whether your meaning is that because of the high altitude there would be a takeoff weight restriction that precluded filling the tanks or whether that even with full tanks there is a fuel density factor.

This concern I've tried to capture in the qualification "suitable airports", by which I mean airports which can handle an A380. Obviously airports with no long runway, or which are too high, or which are only designed for seaplanes or helicopters would not be suitable...

there is no "suitable airport" qualification in your answer.

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text:
What safety features prevent jets sucking in ground staff or equipment?
There have been some gruesome deaths involving ground staff being sucked into jet engines, presumably because the engine thrust was set well above idle. Are there safety features (besides prudence on the flight deck) that are designed to mitigate this risk?

prudence & procudures on the apron

Related: Why not mount airliner jet engines above the wings?

No, there are no safety features. Only safety procedures on the flight deck and on the ground.
Basically it all boils down to that nobody may go near any aircraft (jet or prop; they are both similarly dangerous) that may have engines running. When starting the engines, the pilots first turn on the beacon (the red flashing lights on the belly and tail), then check the ground crew has left and only then start the engine(s). And similarly upon landing, the pilots shut the engines down, wait a bit to let them spool down and turn off the beacons; then the ground crew should ask (via radio or the wired intercom connected to a socket at the nose) whether the engines are indeed off and only then they may start working.
Since start-up normally only happens after push-back, so away from the terminal, there is usually no risk then. Upon arrival however the ground crew needs to come to the aircraft relatively quickly and insert chocks to the wheels, so the correct procedures are important.
Here see a recent accident where ground worker was injured because the procedures were not followed (he was coming from the rear, so he was only blown away, not sucked in).
In that incident, the engines were at idle. They are still very dangerous in that case. I found an Airbus document which shows danger areas, for A320 with CFM56 engines, at idle as:

suction danger 2.2m (7.2ft) from engines (semicircle forward and to the sides of the engine and back to 1.5m behind the inlet) and
exhaust danger to 55m (180ft) behind the nozzles with 30° spread with exhaust velocity exceeding 105km/h (65mi/h) for 17m (55ft) aft of the nozzles.

At full power the suction area grows to 5.9m (19.5ft) radius and the exhaust danger to 275m (900ft) with velocity over 105km/h down to 150m (500ft) aft.

Ground operations are complicated and dangerous. You can find some details about risks and hazard zones associated with operations on the ground, here.
Precautions taken to minimize risk are (among others:)

Everyone must be clearly visible. Ground personnel always wears high visibility clothes including high visibility vests, and trousers with high reflectivity stripes (even during the day.) The tarmac is well lit. Operations cease on extremely low-visibility situations.
Cockpit to ground communications: The ground will inform the cockpit that they are cleared to start-up the engines. The ground crew will make sure that no person or object is in the hazard zones of the aircraft.
A special indicator light will be on when the engines are about to be started/are running (for example: the Anti-Collision light for the B737, and the Beacon light for the A320.)
Jet blast deflectors are used where necessary. This went infamously wrong in this instance.
The spirals painted on jet-engine spinners  are used as visual cues from the ground crew that the engine is on (this is somewhat anecdotal: the spiral on a spinner that is slow-spinning because of the wind will be still visible as a spiral but the spiral becomes a gray point if the engine is spinning while it is in operation.)
Airport signs and ground markings, such as these:

Ground marshaller and wingwalker signals

All the signs in the world are no match for human stupidity.

Also, most airlines paint danger zones on the pavement that ground crew are required to stay out of.

@Lnafziger is it airlines that paint the pavement or airport that paint the pavement?

@vasin1987 Good question!  I believe (but am not sure) that the airlines lease the gates and are responsible for their own painting because they can place equipment wherever they want it, etc.

Spool down times for various engine types allow ramp agents like me to routinely avoid being ingested.i.e when
Aircraft is coming up the j-line via direction from ramp agent the rest of the crew maintains a safe distance from the approaching aircraft until appropriate time passes per aircraft at arrival. You can only get ingested once in your life but you can get blasted by jets several times.

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What are en-route VHF marker beacons (75 MHz)?
ICAO Annex 10, Volume 1 contains a section that gives the specification for en-route VHF marker beacons. What are they?
I suspect they are a relic of the past. Are they still in use anywhere in the world?

Related

Some other related info

En-route marker beacons are close relatives of the outer/middle/inner markers used on ILS approaches. Airway markers use the same audio frequency as inner markers, and some older equipment has indicators for airway/outer/middle. Older versions of the FAA AIM discuss marker beacons, but later versions omit them.
From Wikipedia:

From the 1930s until the 1950s, markers were used extensively along airways to provide an indication of an aircraft's specific position along the route, but from the 1960s they have become increasingly limited to ILS approach installations. They are now very gradually being phased out of service, especially in more developed parts of the world, as GPS and other technologies have made marker beacons increasingly obsolete.
The airway marker was used to indicate reporting points along the centerline of now obsolete "Red" airways
They are only used on a few instrument approaches anymore, to mark positions along the inbound course, when there is only one marker present

The example cited on Wikipedia (KSEE) used to have a marker as part of the LOC-D approach, but it appears that this was replaced with the YAGSU waypoint (and more recently, the DEBEY waypoint). Another example is KSLE where the ARTTY intersection on the LOC BC 13 approach used to have a marker but no longer does. I haven't been able to find any current procedures still using one.


text:
Can an amateur-built aircraft ever be used for commercial activities?
There are some non-recreational activities, such as aerial photography, wildlife observation, environmental monitoring, etc., that seem well-suited to certain amateur-built aircraft.  The open-cockpit Lockwood AirCam, which I understand was specifically designed with back-country nature photography and videography in mind, is just one example.  Yet FAA regulations relating to airworthiness certificates appear to make no allowance whatsoever for an amateur-built experimental aircraft to be used for non-recreational/non-educational purposes.  Am I misreading the regulations?  Is there a legal way to use a homebuilt airplane for, say, commercial aerial photography?

If you build an aircraft and use it for commercial activities, you are not an amateur, even if what you do is illegal.  Potentially, an amateur could build an aircraft and then give or lend it to someone who used it for commercial activities.

Not necessarily.  You would have to comply with §91.319 (a) which states:
No person may operate an aircraft that has an experimental certificate—
(1) For other than the purpose for which the certificate was issued; or
(2) Carrying persons or property for compensation or hire.
So commercial activities which don’t require carriage of a person or property for compensation or hire are permitted in an experimental category airplane, so long as it was not certified as a light sport under §21.191(i) which limits such aircraft to be used only for glider tow or flight instruction, subject to the limitations of §91.319 (e), (g).

You just need an faa letter of authorization. That’s how you can charge for rides on powered parachutes, weight shift etc

According to the Experimental Aircraft Association (EAA), aircraft with Experimental/Amateur-Built airworthiness certificates cannot be used for commercial purposes. However, I cannot find an FAA reg that specifically says that. (Anybody else know of a reg that says that?)
There are other grey areas as well. For example, what if your insurance is requiring dual instruction in the type before they will issue you a policy? The CFI would be using your aircraft for commercial purposes, even if you can legally claim you're the Pilot-in-Command.
However, the FAA talks about what things you cannot do without a commercial pilot license -- fly passengers or cargo for hire. My suggestion is that if you want to use your amateur-built aircraft for commercial photography, call your local FSDO and ask about that. Be nice to them and you'll be impressed how nice they can be to you.

91.319 and 21.191 are the regs you're looking for. There's no problem with instruction, by the way; 21.191 specifically allows it, and if it's your aircraft then the CFI isn't the operator anyway.

the local FSDO can’t give waivers for that kind of thing. The only way to do it would be to get a Legal Interpretation from the Office of the Chief Counsel, but since the regs are unambiguous that’s not likely to happen.

Talking to your FSDO is not about getting waivers. You don't need a waiver to do something that is not prohibited by the regs, and the regs do not prohibit aerial photography. Private pilots are already allowed to operate aircraft for aerial photography and get paid for the photos, not the flying.

I wasn't aware of that last statement ("private pilots are allowed ... to get paid for the photos").  Is there an FAA legal interpretation or advisory circular that makes that position clear?

@GrantPetty That was true, but it isn't any more. The FAA issued two interpretations: one said a private pilot could operate an aerial photography business; the other said it needed a commercial pilot. The tiebreaker is the Perry interpretation which says you need a commercial pilot. Makes sense to me: how could flying possibly be "incidental" to an aerial photography business?

Actually, that argument is easy to make if you have kept up with the technology and know that you can automate the photography portion of the work. That letter is 8 years old. Quite a bit has changed since then.

A experimental aircraft can be used by a corporation for busines purposes.  However, an experimental aircraft cannot be used for commerical purposes such as paid passengers or paid cargo.

Welcome to aviation.SE! For questions like this it's usually helpful to link to a regulation or another official, reliable source.

I'd think that flying such an aircraft in an airshow, to show off its capabilities to pilots/builders who might purchase the plans/parts, would be both allowed, and also categorized as "business purposes."

@RalphJ A corporation generally won't use an Experimental Amateur-Built, except possibly as a club a/c. For your use, it would have an Experimental Market-Survey  certificate. This is what most kit manufacturers' factory built planes have. If they just want to use it for show and advertising, there is Experimental Exhibition (this is what most ex-military a/c have). If they're doing flight test (of the a/c or components on the a/c) they get Experimental R&D. Each has its own set of restrictions.

So I asked Phil Lockwood about this. His take is that if you charge say a commercial cameraman for flying them to do photography then you will cross the FAA line. However if you use the Aircam as a tool for your own purposes, then you are unlikely to have a problem. A number of books have been published using an Aircam for aerial photography.
https://www.amazon.com/Chasing-Lewis-Clark-Across-America/dp/0974920711

and who's this Phil Lockwood?

@Federico: is the guy who designed this.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Why does Ryanair always fill its flight plans with the same remark?
With my current position, I have access to samples of ATC recordings, including all the flight plans received by a FIR. Parsing these recordings, I noticed that Ryanair always put the following sentence in both ICAO field F18/RMK and ADEXP field -RMK:

PAX SCHEDULED FLIGHT CONTACT +353 IRISH PHONE NUMBER

Why does Ryanair do that?
Note: the field "flight type" is also filled, and contains the letter S for Scheduled, thus my surprise.
Note2: +353 is country code for Ireland where Ryanair is based.

It's a contact number for their "HQ". Putting it in the remarks ensures they are easy to get on the phone if necessary for any issue/emergency.
Regarding the redundancy of putting "SCHEDULED" in the remarks - I assume it's for the same reason - ease of locating information.


text:
External stores on the A-10 Warthog
I would like to understand the hardpoint use for the A-10A during the 1980s. From various official and model-building sources, there are eight wing and three fuselage pylons, all permanently installed, with a total capacity of 16,000 lbs. It seems that the sum of the individual loads is greater than that, with restrictions on which pylons can be fully loaded at the same time. I've seen them numbered 1 to 11 from left to right, with 5 to 7 being the fuselage pylons.

I've variously read that 4+6+8 or just 4+8 were wet hardpoints for fuel tanks. Yet a 600-gallon ferry tank would be about two tons, more than 4+8 are supposed to carry. Was the 600-gallon tank only carried on the centerline, and if so what tanks were carried on the wings? Is there a difference between the A-10A and the A-10C in this regard?
As I understand it, external tanks were not rated for combat during the Cold War era. This seems understandable considering the crowded potential battlefield in the Fulda Gap. Was there a difference in nominal capacities for combat use and ferry tanks?
3+9 can carry triple racks with AGM-65. Not 4+8 as well? The weights would seem well within limits.
Could 6 be used at all if 5+7 were loaded, or was it either-or?

Basically my question is how much each pylon could carry.
The underlying question is what a historically accurate yet visually interesting loadout for a Cold War tankbuster would be. Mavericks, Rockeyes, what else?

There are several sizes of external fuel tanks. For example the USAF uses or used 275, 330, 375, and 600 gallon fuel tanks (and probably others) over the last several decades. 600 gallon is afaik only used for centerline use and not combat rated.

Ideally you don't want to use external tanks on combat sorties. Not only does it limit the number of weapons you can carry, it also reduces your turning capabilities and makes you a bigger and juicier target (the external tanks aren't self sealing or armoured, unlike the internal tanks). If you need a ferry tank to the combat area, drop it before entering combat. That's been SOP since the invention of such tanks. In fact if you zoom in on one of the photos in the PDF linked to from the URL you posted you can see smaller tanks on the inboard stations, plus a 600 gallon tank on the centerline.

probably because those hardpoints weren't wired for the missile control connectors.

if they could be used all at once it'd severely limit the loads on either. I've never seen photos or video of A-10s in that configuration.

Thanks. I've seen non-official references to 600-gallon tanks under the wings, so any official source for your first point would be very nice.


text:
Is "passenger loading bridge" a synonym to "contact stand"?
In a master plan of an international airport, which is already approved by the client, I face some confusion between the terminology of the PLB and the contact stand.
Sometimes they're mentioned just as the same component, not like other locations. I assumed a sort of a conflict in the master plan but I'd like to confirm this please.
Is there any  benchmark like ICAO or IATA that defines such components, e.g., the gate, rotunda, PLB, contact stand, etc.?

Have you consideder asking the client for clarification?

I'm working within Client's PMC firm who joined the project recently.


text:
Descend via STAR, after getting crossing restriction previously
The ATC issues "Cross BHAWK at FL240" initially. After few minutes, the ATC instructs "Descend Via FYTTE5 arrival". Should we comply with the crossing restriction at BHAWK, or the restriction can be omitted?
The JO 7110.65Y says

Clearance to “descent via” authorizes pilots:

To descend at pilot discretion to meet published restrictions on a STAR.

and

“Climb via SID except after Baret, maintain flight level one niner
zero.”
NOTE1. Considering the principle that the last ATC clearance issued
has precedence over the previous, the phraseology “maintain
(altitude)” alone cancels previously issued altitude restrictions,
including SID/STAR altitude restrictions unless they are restated or
modified, and authorizes an unrestricted climb or descent. Speed
restrictions remain in effect unless the controller explicitly cancels
the speed restrictions.

However, the example given in "descend via" does not say anything about "previous assigned crossing altitude." And the note given in "climb via" example only explains the phraseology "maintain" would cancel previously issued altitude.
Is there any FAA document stating the altitude restrictions assigned previously can be omitted or still valid, after getting "descend via" clearance?

If in doubt, there's no doubt: ask ATC for clarification.

Since the STAR lists an upper limit at BHAWK of FL260 and a lower limit of FL220 there's no reason you couldn't comply with the clearance to cross at FL240. And in systems I'm familiar with, if you load the STAR in your FMS with VNAV engaged it will plan your crossing of BHAWK at FL240 (half way between the limits.)

@Gerry That isn't universal; the 737 FMC will stay as high as possible as long as possible for fuel efficiency, so if being at 260 at BHAWK doesn't create a problem for later restrictions, that's what it will do if the pilot didn't overwrite the 260-220 altitude with the first "at 240" clearance.

@RalphJ You are correct.  There's a lot of variability between systems.  Where it gets interesting is with the multiple crossing restrictions.  The FMS (per the current MOPS) will try to maintain a constant vertical path angle between restrictions.  In the above, since FYTTE is a cross at 11000 it will try to straight line the vertical path between BHAWK and FYTTE as long as it meets the restrictions on the intermediate waypoints.

The restriction to cross "BHAWK at FL240" is overridden by the controllers latest clearance to "Descend Via FYTTE5 arrival", unless they  include the instruction  descend via "EXCEPT MAINTAIN FL240".
FAA Climb Via/Descend Via Speed Clearances Frequently Asked Questions, page 6, questions 8.
If unsure, you should query ATC though.

Or, "cross BHAWK at FL 240 and then descend via..." might be the way they'd assign that. But that is certainly not the same as just "descend via," which does cancel the "at 240" clearance unless it's restated. Definitely worth considering asking, "so understand you don't need BHAWK at 240."

And, welcome to AV.SE, by the way!

Thanks so much!
Yes “Descend Via” clearances require a careful watch. There is certainly a significant threat of altitude bust.
On the Airbus, for example, it would be easy to take a heading for traffic and then get cleared back on the arrival but if you didn’t check the modes you would still be in “open descent” which would not comply with any restrictions on the way down to the altitude set in the FCU.

Just wondering which publication says "descend via STAR" would cancel previous assigned restrictions.

no problem we are cleared descend to the bottom altitude of the STAR, but the FAQ does not answer "descend via STAR" would cancel previous assigned restrictions or not.

You can always query ATC, but I generally reserve radio transmissions for clarifying apparent or potential conflicts.  In this case there is no conflict, so why not save your breath and simply cross at 240?  You also avoid the dreaded snarky response...

In JO 7110.65, 4−2−5. ROUTE OR ALTITUDE AMENDMENTS.  b. When route or altitude in a previously issued clearance is amended, restate all applicable altitude restrictions.
The example given:

“Amend altitude. Cross Ollis intersection at or above Three Thousand;
cross Gordonsville V−O−R at or above One Two Thousand; maintain Flight
Level Two Four Zero.”
(Shortly after departure, altitude restrictions are no longer
applicable, the controller issues an amended clearance as follows):
“Climb and maintain Flight Level Two Four Zero.”

When issuing an amended altitude (cross BHAWK at FL240 >>> Descend via STAR to bottom altitude), ATC should restate all altitude restrictions if applicable. If not restated, it's no longer needed.


text:
What differences are introduced between ICAO Annex 10 volume IV amendment 85 and amendment 89?
What changes have been made to ICAO Annex 10 volume IV (Surveillance Radar and Collision Avoidance Systems) between amendment 85 and amendment 89?
I only have access to amendment 89, but I have some material referring to amendment 85. What is the difference between these versions, what has been changed to ICAO Annex 10, volume IV by amendments 86 - 89?

I've got copies of both Amdt 87 and Amdt 89.  Amdt 87 shows no change from 85.  Amdt 89 does show changes, but the summary of changes is "Surveillance systems".  I couldn't see any changes at the Table of Contents level, but there are numerous small changes throughout.

@mins  Thanks. That list answers DeltaLima's question as Amdt 89 is the only change after Amdt 85.

With help of Gerry and Mins, it became clear that Amdts 86,87 and 88 did not introduce any changes to Volume IV of Annex 10.
Therefore any differences between Annex 10 Vol. IV Amdt 85 and Amdt 89 would be introduced by Amendment 89. From this documentPDF it can be seen that the changes were distributed in state letter 2014/21.
Digging a bit further I found the
minutes of an ICAO Communication Navigation and Surveillance  Sub-Group (CNS SG)PDF  meeting which included the state letter in Appendix B. You can find it from page 56 to 91.
Amendment 89 contains over 30 pages of changes to Volume IV of Annex 10 and that was more than I had hoped for; needless to say I am not copying all that information into this answer. A summary of changes can be found below.

General changes

Various recommendations and clarifying notes added.
Various editorial changes

Chapter 3, Mode S Surveillance

Revoking of the Mode A/C/S all-call interrogations after 1 January 2020.
Introduction of new data parity overlay ("Modified AA") in
transponder and Overlay Control (OVC) bit in Mode S uplink protocol.
Changes to Type Control (TCS)

Chapter 4. Airborne Collision Avoidance System

No significant changes

Chapter 5. Extended Squitter (ADS-B)

Introduction of ADS-B 1090ES Version 2

Chapter 6. Multilateration

Spectrum protection requirements


text:
What are the regulations for lighting fixtures around an airport?
I work for a company that is right next to an Air Force base and we were wondering what and if there are regulations for the lighting fixtures that we can install on our lot since we have a couple of lights that are out of service and we were looking into upgrading them to LEDs
what is the temperature limit etc etc
I don't know much about aircraft regulation so i get lost in all the documents.
thank you!

Welcome to the site! Just to be clear, your company is outside the Air Force base and you want to make sure that any lighting in your parking lot is legal and doesn't interfere with aircraft operations. Is that correct? And which country are you in?

Yes!
we are located in the U.S.

Have you considered walking next door and asking? I know it's not as easy to get on a military installation as it used to be, but if you pick a quiet time (living next door, it should be easy to figure out when that it), I'm sure you could chat with the MPs at the guard post, tell them your need and ask who you should contact. You'll probably get a phone number for the base commander or someone similar who will point you in the right direction.

If this were a public use airport I'd say make a plan, make some drawings, and then contact the tower and talk to somebody. Odds are you would get directed to the local FSDO, but its unlikely you would have problems if the airport doesn't have any deed restrictions on your property. In the case of the US Air Force I agree with @FreeMan, see if you can get the number of the base commander and ask directly, they really don't have to follow FAA airport rules (although they usually do).

Thank you for the response @FreeMan but i went next door and they couldnt tell me that information!

It was worth a shot. Good on ya' for asking them!

To start you off there's these two:
14 CFR Part 139 - Certification of Airports and
14 CFR Part 157 - Notice of Construction, Alteration, Activation and Deactivation of Airports.
Part 139.311 covers all the lighting related requirements.
Part 157 is there just so you can inform the FAA about the changes you're going to make in the airport.
for specifics about LED lights, I would suggest looking for Advisory Circulars with LED lighting for airports in particular.

So i read the documents and it appears that they answer the question for lights on the field not outside
we are looking at a lighting fixture with temperature 4000k and 21000 lumens


text:
Nemesis Champion Racer
The Nemesis Formula 1 racer is a small plane 1991 to 2000 champion setting a lot of speed records.  It went over 260mph, it was fast for its size and engine.  Its fast wing helped it fly fast.  How exactly does its wings fly so fast and smooth?

Three major reasons:
1) Advanced aerodynamics using CFD analysis and wind tunnel testing as well as construction with lightweight and largely seamless composite materials provide a very 'slippery' airframe that doesn't create a whole lot of induced or parasite drag for a given speed.  Very thin, high aspect ratio wings are used.  Access panels are kept to a minimum.  All joints are smoothly blended together.  Landing gear is retractable and fully enclosed.  Fasteners are flush and heads taped over.   Gaps and edges are puttied or taped sealed prior to flight.  The airframe exterior has been waxed and highly polished for as smooth of skin as possible.  The entire aerodynamic envelope has been very carefully studied and optimized to minimize areas producing turbulence and as a consequence parasite drag.
2) Minimized flat plate area.  The cross section of the aircraft has been kept to the bare minimum needed for structures and systems and virtually nothing for crew comfort.  The cockpit is really tight and built around the shape of the pilot's body - even to the point of requiring the pilot wear an oxygen mask connected to a fresh air vent to facilitate breathing.
3) Sacrificing docile handling characteristics.  The wings and flight controls are maximized for high speed flight as opposed to easy and forgiving flight characteristics.  If you look at a Beech Bonanza or a Piper Archer, you'll note that they have very thick wings which handle well at low speeds and give an inexperienced pilot a lot of forgiveness in sloppy handling before departing from controlled flight at the expense of producing a lot more induced drag.  This isn't the case of the Nemesis and it demands a very good pilot at the controls to fly it at the correct speeds and numbers with little margin of error.


text:
What is the longest possible flight on earth?
If every place on earth had a runway. What would be the longest possible flight? What would the distance and flight time be?
Between two point on the equator? Between the north and south pole? Something else? Consider winds as well.
Is there a commercial plane that could do it without refueling? What airplane and how long would it take.
What would the crew of such a flight look like.

Welcome to Aviation.SE it's not clear, but it sounds like you're essentially asking what is the greatest distance between two bits of land and is there a plane capable of flying it. If a plane's capable of air-to-air refuelling and had multiple crews it can fly pretty much indefinitely.

Related: The top 10 longest range airliners in the world. The longest path between two points on Earth, when flying at 11 km altitude is about 20,071 km. So the answer is no airliner is capable of that without a very favorable wind, but legally it wouldn't be permitted.

Between any two points on Earth regardless if they are on sea or land and regardless if they have an airport or economic reasons to do the flight. I am looking for an upper bound on the longest flight

I'm voting to close this question as off-topic because while this question is about plane range compared to Earth circumference value, it can be answered easily without expertise. You may edit it to make it more specific to aviation (please don't add comments to refine your post, edit it).

You can fly around the world without refuelling, albeit not in a commercial airliner. A commercial airliner could not do this (indeed, why would one ever design such a plane, seeing as not every place on earth has a runway?). Aerial refueling allows for flying nearly indefinitely (until the crew runs out of food, but you can store a lot of food aboard large military aircraft).

What would the crew of such a flight look like. - oh, around 5'10, medium build, handsome to some people's eyes. (sorry, couldnt resist)

Either way, not voting to close because I don't think it's necessarily off-topic, but I did downvote because it is "not useful".

@mins The 777-200LR not only can fly that far, but has. It can't fly that far in passenger service though, as I don't think any regulations exist that would allow a 22 hour, 42 minute flight, even with an augmented crew. The plane that set the record had eight pilots on board.

@reirab: Fair enough! Good find.

This is only half related to aviation, but I'll bite.
As the Earth is close enough to a sphere (but not exactly..) it is simplest to assume that the longest flight would be from one end of an antipode to the other.
According to this site, such a flight would be approximately 20,000 km:

There are no non-stop scheduled flights between any two antipodal locations by commercial airline service. A hypothetically perfect antipode flight would be Tangier Ibn Battouta Airport, Morocco to Whangarei Aerodrome, New Zealand (approximately 20000 km flight).

The Boeing 777-200LR is the aircraft with the longest range at just under 17,400 km (but see also this question which explains why that number can change). So with present technology (or economics), such a flight is not really a possibility.

A very good answer to a very poor question!

Yo may also mention ETOPS that would likely make the flight longer than the great circle.

@mins ETOPS does not increase the aircraft range. An ETOPS-certified aircraft is allowed to fly far from airports, that's all.

@Quentin mins means that the flight path might not be able to take the great circle route due to the ETOPS regulations (which does indeed effectively shorten the range between cities that can be connected.) That said, the 777-200LR's ETOPS limitations don't meaningfully restrict almost any possible flight. Only a few parts of Antarctica are not covered.

Note that the range listed here for the 777-200LR is assuming a full load a passengers. With limited payload, the 777-200LR can - and has - flown more than 20,000 km. It currently holds the world record at a bit over 21,600 km. This required an 8-pilot augmented flight crew, so it's probably not legal in passenger service.

@reirab: In addition, as you know, alternate airport and fuel reserve would need to be planned for the flight to be dispatched.

@mins Yes, that's true. The linked map shows the parts of Earth that are within the allowed flying time range of possible alternate airports (which is basically everywhere except some parts of Antarctica.) Given the location of the non-covered area, I guess McMurdo Station doesn't count as a valid alternate. :)

@reirab: I must admit I was a bit pessimistic, ETOPS 180 is already covering most of the planet. Thanks for pointing out :-)

@mins Yeah, thankfully, there are lots of tiny islands lying around in various parts of the Pacific and also a few in the Atlantic. And Svalbard, Greenland, Canada, Russia, and Alaska cover the Arctic pretty well.

Given that the Earth is a slightly oblate spheroid, the longest flight is 24,874 miles, starting from somewhere on the equator, following it, and returning to your starting point.


text:
Do big complicated aircraft check the DI?
When I was learning to fly (on PA38s) I was taught to check the Direction Indicator against the magnetic compass every 15 minutes or so, because the DI can drift. I may not have done it that frequently after I got my license, but I still figured it's a good idea.
Do crew of airliners and other complex aircraft still do this? Or is there something else that fixes the problem?

The main difference is that airliners and other more complex aircraft will have much more sophisticated navigation equipment. Instead of a "simple" vacuum-powered gyroscope, they have things like ring laser gyros that are constantly measuring acceleration and orientation of the aircraft.
There is still an amount of drift, but it's much less. Honeywell claims a drift of less than 0.0035 degrees per hour, so after a full day that's still less than 0.1 degrees. The system is initialized before each flight and on modern aircraft it's constantly adjusted based on input from GPS and DME.
Airliners are also usually flying between waypoints under ATC supervision rather than following headings on their own. If there were a heading alignment issue, ATC would notice. But it would probably only be on a single unit and cause enough position error that the system would detect the error and alert the crew.

The gyros are also synched to a magnetic source.

@MichaelHall Not true for larger airliners with a full ADIRS/ADIRU (e.g. Airbus, Boeing), which derive magnetic heading from IRS true heading and a global magnetic declination model. Smaller airliners with a simpler AHRS (e.g. Dash-8 Q400) can slave their heading to the magnetic measurements from the flux valve.

@Bianfable, consider my comment revised to "may" be synched...  Anyway, this additional detail would be good to capture in an answer.


text:
Do FAA Regulations apply to government aircraft?
In this answer it is claimed that government aircraft in America are exempt from FAA regulations.
I'm aware that military aircraft do not need to follow FAA regulations. Is there also an exemption for aircraft owned and/or operated by branches of American governments?

Related:  https://aviation.stackexchange.com/questions/31659/what-are-the-rules-for-public-use-operations

"military aircraft do not need to follow FAA regulations" is overly broad, potentially misleading, and not entirely correct.  Certainly there are many parts not followed, but just like part 135 operators don't have to follow 121 rules, the military has it's own regulations to follow.  And when operating in the National Airspace System you better believe they follow the same rules.

In 14 CFR 1.1, we find two definitions:

Civil aircraft means aircraft other than public aircraft.
Public aircraft means any of the following aircraft when not being used for a commercial purpose or to carry an individual other than a crewmember or qualified non-crewmenber:
(1) An aircraft used only for the United States Government; an aircraft owned by the Government and operated by any person for purposes related to crew training, equipment development, or demonstration; an aircraft owned and operated by the government of a State, the District of Columbia, or a territory or possession of the United States or a political subdivision of one of these governments; or an aircraft exclusively leased for at least 90 continuous days by the government of a State, the District of Columbia, or a territory or possession of the United States or a political subdivision of one of these governments. …
(2) An aircraft owned or operated by the armed forces or chartered to provide transportation to the armed forces if - …
(3) An aircraft owned or operated by the National Guard of a State, the District of Columbia, or any territory or possession of the United States, and that meets the criteria of paragraph (2) of this definition, qualifies as a public aircraft only to the extent that it is operated under the direct control of the Department of Defense.

The most visible example of a “public aircraft”, beyond military and diplomatic flights, would probably be police helicopters.
As to the “exemption”, if you look through 14 CFR, you will find many sections and even some entire Parts that only apply to “civil aircraft”.
For a trivial example, 91.105(b) only requires pilots of civil aircraft to wear shoulder harnesses during takeoff and landing, ergo pilots of public aircraft do not—though they probably do so anyway unless there’s a mission-related reason not to.
That’s the rub: Public aircraft voluntarily follow most of the rules, most of the time. They just know that when they have a compelling reason to break the rules, they can’t be hassled by the FAA for it.

Technically I don't think you even need a pilots license to fly an aircraft used for police activity, but nearly every one I've seen still requires it.

@RonBeyer Not according to the FAA, but the owning agency will certainly require one. That hole was obviously intended for the military, which has its own system.


text:
Is the air bleeded from the engine to maintain cabin pressure for airlines heated or cooled
Is the air bleeded from the engine to maintain cabin pressure for airlines heated or cooled.  If heated, what device is used, if cooled, what device is used and in both cases how much energy does it draw for both the former and the latter

Bleed air is hot, very hot, it needs to be cooled before it can be used for pressurization.

Related: How hot would pressurized air get if the air conditioning failed?


text:
Are cockpits waterproof to prevent spills
Are cockpits waterproof, i.e. designed with the fact that a pilot might spill  a hot or cold drink over the instruments by mistake?

Minor nit, but a waterproof instrument panel (say) wouldn't prevent spills in the cockpit. The risk of spills is unchanged by whether the instrument panel is waterproof or not. What changes is the consequences of a spill. If anything, if everything is waterproof that might make pilots and others in the cockpit be less careful, because they know that the consequences are likely to be less severe.

Fate is the Hunter?


text:
Are there certain areas where a pilot can jettison his/her external fuel tanks?
When a pilot feels the need to jettison their external fuel tanks, do they have to wait until they are above a certain area, or can they just drop them wherever they please?

Not really military, but in the United States I can drop anything I want from my aircraft as long as I take care not to injure people or property.

Are you asking about a specific country or jurisdiction, or is it a general question?

@Ron Beyer: But I imagine you could be cited for littering.  Theoretically, at least.

That's local enforcement, the FAA doesn't care about it at that point, so they don't regulate it :). There are a lot of local flying clubs that have drop contests throughout the year, usually a team of people (pilot/bomber) dropping things like watermelons or oranges at a target. Good old fashion fun if you can find one to watch or participate in.

@Pondlife just a general question

@jamesqf Do you suppose they cited this pilot for littering?

@TomMcW: Given that they jettisoned the bomb to avoid a potential explosion upon landing, I'd say they'd have had a pretty solid necessity defence for that.

This depends where in the world you are, over civilian US territory military planes chose to operate under the FAA FAR's (although they are not explicitly legally required to), as such its pretty cut and dry

Sec 91.15 Dropping objects.
No pilot in command of a civil aircraft may allow any object to be
  dropped from that aircraft in flight that creates a hazard to persons
  or property. However, this section does not prohibit the dropping of
  any object if reasonable precautions are taken to avoid injury or
  damage to persons or property.

Elsewhere in the world the rules may vary. There may also be rules about dropping tanks over open water due to their being residual fuel in the tanks.
This question covers what happens to them after they are dropped.
This thread would indicate that they are actually not dropped all that often.

That FAR doesn't apply to military aircraft. The wording is "pilot of a civil aircraft", but 14 CFR 1.1 defines military aircraft as "public aircraft". See this question for more details.

The FAR's (unless an exception is applied for) do apply to military aircraft operating in FAA airspace. See this question for details.

All the answers on that question say (to me) that the military generally follows FAA regulations as a matter of policy, even though legally they don't have to. Military aircraft are explicitly public, not civil.

Pondlife is correct. Although the US Military tends to follow ATC guidance when flying around in ATC's controlled airspace, they don't have to. They can declare MARSA whenever they want. Nor are they (or any other "public" aircraft) subject to FARs. And, even more "technically", US airspace belongs to the military, and they grant permission to the FAA to control it. At any time (see 9/11) the military can pull back control. So, there is no "exemption" to be "applied" for by the military.

Verbiage has been updated to reflect.


text:
Could there ever be a fully solar powered airliner capable of transatlantic flights?
Could a new or a modified existing airliner, e.g., a Boeing 737, be fully powered by solar energy and make the normal length trips aviation-fuel powered aircraft make?

The most likely way of achieving that would be a large ground-based solar-to-jetfuel plant, using one of several chemical processes.

Define "solar powered"; oil comes from dinosaurs (et al.) who got so big and scary by eating other dinosaurs that ate plants that ate solar photons.

Are blimps allowed?

To give you an idea of current solar technology: This is a 1 MW solar power plant. You need 90 MW to fly a B747-8, according to this answer. And you need to choose the departure time to fly only on daytime. If the cell efficiency was 100%, you would need only 1/5 of today's cell area. Still a big challenge (solar irradiance is about 1kW/m² in the visible spectrum, on Earth).

@brian Good luck getting a blimp up to Mach 0.75 or so.

@brian not as as far fetched as it sounds, lighter than air has a few advantages but weather would need to be favourable.

Yes. Massive solar array driving splitting seawater into H2/O2 to fuel aircraft. As pjc50 said, you need way too much solar for airplane surface.

Bear in mind that if you don't need to worry about a meat popsicle, you can ditch a lot of weight. NASA, Qinetiq/Airbus, and others have made "aerial satellites" that have endurance numbers in the weeks or altitude limits >90,000 ft (higher than a U-2, and with propellers, not a jet engine). Sending them across the Atlantic seems like a trivial task, the annoying part is takeoff/landing for such gossamer structures.

@NickT The other annoying part is that it takes days or weeks to cross the Atlantic instead of a few hours and the possible payload is negligible. Might as well just use a blimp. 'Aerial satellites' are a neat idea for things that need to keep a very small amount of weight hovering above a given area for an extended amount of time, but they're not quite as useful for flying 200 passengers across the Earth at Mach 0.75-0.8.

The VoltAir is a concept all electric airliner:  http://www.nbcnews.com/id/43556583/ns/technology_and_science-luxury_tech/t/voltair-electric-passenger-jet-future/#.WD6fcvmqqko

"Oh No! I see clouds... we are going to die!"

Short answer: No
Long answer: No. Look at the solar impulse project, this is some of the best solar-electric technology that's out there, and it's barely able to carry one person, very very slowly. If you took an airliner, covered it in the best solar cells available and connected it to the best electric engines available it probably wouldn't even be able to taxi.
Some science here: The maximum energy density of the sun on the Earth is about 1300 watts/meters squared. About 30% is lost in the atmosphere so the best you'll get on the surface of the earth is about 900 W/m2. The 737, for example, has 102 square meters of wing area, that would equate to about 90000 watts (90KW) of sun energy hitting the wing. The best power conversion we have of solar to electricity we have is about 10%, so you would get at most 9KW of power from a 737 solar array. As we see from this answer it takes 90 MW (megawatts) of power to get a 747 into the air, assuming it takes about 1/3 or that (30MW or 30000KW) to get a 737 into the air, then that array will only generate 0.3% of the electricity needed, and that's the best possible case in the strongest sun. If it's cloudy or at night you are completely out of luck.
Any solution based on current battery technology is addressed here, and it's very much a no at this point.
Theoretically it is not possible that a solar powered passenger airplane could be as good as a jet-a1 powered passenger jet, this is because the energy from the sun is not sufficient even if you had 100% conversion to electricity. If battery technology were to become orders of magnitude better to the point its energy density compared to liquid fuels then it very well could, this is a long way off, the best batteries that are currently lab concepts are about 1/5 of the density of liquid fuel. Once batteries get there then solar power could charge them for the flight. It's actually just as possible that solar power could be used to make liquid fuel in a renewable way from CO2 and other elements in the environment. Bio-fuels are solar powered, but we can't make much of a dent in fuel use with them without taking food off of people's plates, and personally I'd rather eat!

I disagree with this answer purely because it discusses current technology and current power conversion "best case": when the question is asking for "Could there ever". The question therefore becomes a question of whether a more "best case" 80 kW (assuming a larger wing and 80% efficiency) is enough for an aircraft in cruise flight. Batteries (charged by land based solar panels) could supply the takeoff power, supplemented in the air by solar power for cruising. I suspect the answer is still no, but not quite for the reasons you give

@JonStory even 100% efficient solars will only have about 3% of the power needed to get B737 up into the air.

@ratchetfreak if you read my comment again, I'm saying that "getting the 737 into the air" could be assisted by batteries, charged by solar power on the ground. Once at cruise altitude, an airliner uses significantly less power. And, of course, there's nothing to say that a larger wing is out of the question, nor solar panels on a flattened body design. I'm not saying those things would necessarily be enough, just that this answer only addresses the present

you can use the body of the plane to put panels too, change the shape of the plane to get more lifting surface and more panel surface, slow down the plane a bit to get less drag, and use top of the line solar cell, with 44% efficiency instead of a mere 10%

would be interesting to see a calculation on how light the aircraft would have to be to enable a transatlantic flight with 100 people on board and with current solar panel and battery technology. If the weight would have to be negative, its safe to say it's impossible. However, if the weight would have to be only very low, it's merely improbable...

Just a couple of nits.  First, the best commercial PV cells today are about 22% efficient, not 10%: https://cleantechnica.com/2015/10/03/most-efficient-commercial-solar-panels-in-usa-to-come-from-solarcity/  Doesn't change the bottom line, though.  And second, theoretical limits don't allow 90% efficiency.  IIRC about 50% is the best that can be done.

@JonStory Staying in the air uses less power than T/O, but not 30 times less. Even with 100% efficiency at noon at the equator in the summer, it's still not ever going to be enough (well, assuming we exclude the "sun going red giant" thing mentioned in a comment on another answer... that might do it.)

@reirab, as I said I assume that would be the conclusion too, but I don't feel this answer explains that fully, even without exploring how much lighter/slower the aircraft would have to be, and potential weight savings from future solar and battery technology

Forget about getting into the air for a moment.  (Assume we have anti-gravity or some similar handwavium.)  It should be pretty easy (if you're into aerodynamics, anyway) to calculate your airliner's max speed from the CdA and the power available from solar cells.  My guess is that it's going to be something under 60 mph, not 600.

You assumed that solar airliner would have same payload/wing area ratio as 737 while all current solar planes have already demonstrated it's done otherwise. Rest of your post is just a consequence of this mistake.

I assumed nothing @Agent_L, I'm answering the question as I understood it, which is can you power a large passenger airplane with cargo off of solar energy. Sure, a plane with a giant wing, 1/4 of the passengers of a 737 with no cargo but toothbrushes could probably be built, but then it would take 48 hours to get from London to New York instead of 8 and that's not really what people would want.

@bogl: I think what is meant by "similar to a 737" is that the plane would carry a similar number of passengers the same distance in about the same time.  What it's shaped like is irrelevant, as long as you can fit people in it.

@jamesqf Indeed. I said nothing about shape, just payload, speed, and range.

To cover a current-design airliner in solar cells and hook them up to electric engines spinning the fans will not work. Ever. Read @GdD's excellent answer for the reasons.
But today's car is also not a horse buggy with a gasoline engine. It has evolved and adapted to the possibilities. The same needs to happen to the airliner. Now let's look at what is possible. Looking back at the historic developments makes sense here, because the early pioneers also had very heavy and low-powered engines to work with, and still they could cross the Atlantic.
The first Atlantic crossing was planned by a Zeppelin crew in 1918, but the German government banned them from flying. So it fell to a British copy of a Zeppelin, the R-34, to cross the Atlantic in both directions in 1919. It had 5 engines of 270 hp each, which corresponds to 1006.7 kW. With a length of 196 m and a maximum diameter of 24 m the surface area available for solar cells would had been approximately 3000 m² which would provide just enough power if we assume solar cells with 40% efficiency and clear weather. Of course, cloud cover, lower solar altitude and especially nightfall would result in much lower power output from the cells. If we make the heroic assumption that the solar cells weigh as much as what can be saved in mass by modern construction techniques, a solar-powered, Atlantic-crossing airship is quite realistic. But it could not board many passengers and would be very slow.
Now to the heavier-than-air department. The Vickers Vimy which Alcock and Whitten-Brown flew across the Atlantic the same year had a wing loading of 40 kg/m². If we use a braced high-aspect ratio wing of the same wing loading, a very lightweight and efficient aircraft is possible. Covering the wing in highly efficient solar cells gives a power loading of 10 W/kg with 45% cell efficiency. How fast can we fly with that power? Let's assume an L/D of 30 and 90% propulsion efficiency, so we have 270 W of propulsive power per kg of aircraft. The minimum power required for flight is
$$P_{min} = m\cdot g\cdot\frac{c_D}{c_L}\cdot\sqrt{\frac{2\cdot m\cdot g}{\rho\cdot S\cdot c_L}}$$
and expressing this in relative terms and concrete values at sea level:
$$270 W/kg = 9.80665\cdot 30\cdot\sqrt{\frac{2\cdot 9.80665}{1.225\cdot 40\cdot c_L}}$$
yields a lift coefficient of $c_L$ = 0.475. This is actually quite low and corresponds to a flight speed of 28.73 m/s or 55.8 kts, something close to the maximum range speed of the Vimy. Covering the flight distance between La Guardia and Heathrow (2993 nm) would take 53.6 hours or two days and five½ hours.
If the sun would not set, a solar airliner would not be impossible - look at existing solar aircraft designs which have similar specs. The assumed high efficiency even allows to carry some payload, but that whole concept only works when the sun is shining brightly. To cover the dark hours, batteries must be taken along, and then the whole payload must be sacrificed to carry the batteries.
My answer is: If you cross the Atlantic in an airship, solar propulsion is possible in a not-so-distant future. Crossing it in a solar-powered airplane within reasonable time and in an aircraft sturdy enough to fly also in adverse weather will only become possible when super efficient batteries can be carried along to cover the power demands during nighttime. This is currently pure science fiction.

Planes already have mo0re efficient energy storage than batteries: potential energy. Current sailplane endurance record stands at 56 hours which clearly includes nighttime when energy gathering is very limited.
BTW, 2.5 days for crossing Atlantic still beats Queen Mary : )

@Agent_L: Do the numbers yourself. Even going up to record altitudes buys you a few hours, at most. The endurance records were flown in rising air before mountain ridges (or even sand dunes, in one case)

Interestingly, the first cars where all electric - it has taken 100yrs to return to "old" proven technology.

Yes.  Note that your question does not specify how frequently the trips are to be made.
Take your Boeing 737, put as many solar cells on it as you can, connect them to a plant that takes H2O and CO2 out of the atmosphere and turns them into something suitable as jet fuel.  When the tanks fill up, fly somewhere.
From the numbers in GdD's answer the plane will have to sit for years between flights, though.

and worse, he doesn't take into consideration the considerable mass added to the aircraft by those solar panels, which would mean you need even more power...

@jwenting although a good chunk of that weight would be offset by the lack of fuel and pumps/related systems

Still you have a point here, Loren. Leave the solar cells on the ground, and synthesize fuel for jet engines. (see http://theconversation.com/solar-fuels-how-planes-and-cars-could-be-powered-by-the-sun-41938 )

@JonStory which would be more than offset by the extra mass of the batteries as compared to tanks containing Jet-A

@jwenting again, with current technology sure - but without some discussion of other limits to battery power, we've got no evidence that someone won't invent a much lighter, more energy-dense battery or energy storage medium. Whether it's realistic in the short or medium term isn't the question here: the OP asked if it's possible. That means we're talking physics/chemistry to some extent, rather than current technology. Several answers fully or partially show how the power available from the sun is unrealistic for takeoff, but nothing has yet proven that battery power is unrealistic.

I took the OP's question as asking whether it was possible using solar power generation actually on-board the aircraft during flight, but, barring that assumption, yes, this is the correct answer. Technically speaking, we already use solar energy for flying airplanes. It's just that that solar energy was absorbed by some plants or other such lifeforms first, which later died and were converted into oil by lots of pressure over a long time, which was subsequently drilled out of the ground and refined into Jet-A.

@bogl If you leave the solar cells and fuel plant on the ground you won't have any way to get home.

@JonStory you can deny science all you like, but some things are just not possible within the realm of science. And solar panels efficient enough to do this are among them.

@jwenting Assume 100% efficiency, you still can't do it.  An ordinary airplane uses more power than the sun shining on it.

@reirab: Thinking your viewpoint to the end means that we never had any other form of energy than solar here on earth, ever. While this is correct, it is probably not what the question meant.

@LorenPechtel I know, hence having to break the basic laws of nature to make it work...

@PeterKämpf Agreed. That was kind of my point (and I was being a bit tongue-in-cheek about making it.) I was just saying that I think the OP meant to ask about on-board, in-flight generation of solar power, not using solar power on the ground to synthesize a fuel with which to fly a plane later, which, while much more feasible, is effectively what we already do.

@Peter Kämpf: That's perfectly correct.  Other than nuclear & geothermal power (and one could argue about those - e.g. uranium from nucleosynthesis in supernovas), all the power we use ultimately derives from the sun.

Most of the answers assume the sollar energy must be haverested on the plane itself, but there is not enough area there. But why?
It is possible to use a huge ground-based solar battery to decompose water into oxygen and hydrogen. Or just use hydroelectricity - rivers are powered by the Sun. Hydrogen powered airplanes exist. A large commercial hydrogen aircraft could be built by 2020 or about.

Most answers assume solar energy must be harvested on the plane because that is the unique part of this question.  Assuming the solar panels are not on the plane makes it a question of battery capacity, etc, which is addressed elsewhere in questions like http://aviation.stackexchange.com/questions/25281/how-does-the-energy-and-weight-efficiency-compare-between-a-battery-electrical-p/ .  You may also want to provide a link to this question about hydrogen powered aircraft: http://aviation.stackexchange.com/questions/18809/are-there-any-programs-to-build-a-hydrogen-powered-airplane

Does not seen from the question.

It is impossible with today's and tomorrow's technology.
Nevertheless, "ever" is a very, very long time. Nobody can answer 'no' to your question with certainty!

While I think your conclusion is probably right, this answer as currently written is purely opinion with no supporting evidence or justification

@JonStory Which parapgraph are you concerned about, first or second?

Both. You've not provided any evidence that it can't be done with today's technology (GdD's answer is a good example of this), nor any evidence that it's theoretically impossible with any sensibly sized airliner due to the amount of solar energy hitting the earth. Without supporting evidence/justification, your answer is purely opinion

When the sun becomes a red giant and the oceans boil, perhaps the intensity of flux will be more favorable to solar civil aviation.

@JonStory There is a misunderstanding. My point is that there is no such evidence. Nobody can exclude the possibility in the far future.

@bogl unless you postulate that the laws of physics won't apply in the future, a lot of things can be excluded. You'd need a fundamental change in the theory and practice of quantum physics leading to a fundamentally new way of turning sunlight into electrical (or mechanical) energy in order to make the scenario of a solar powered aircraft happen, which seems highly unlikely as it would mean everything we know about matter and energy would have to be proven false, including everything we know works.

@jwenting Changing physics will not help, unless you give up on energy conservation. Even 100% efficiency would not be sufficient to lift an airliner (as we now it) with power coming directly from solar cells. Nevertheless, current physics does not at all exclude the possibility of stronger and lighter materials, as well as drastically improved energy storage. If humans are still around in 500 years, they might have run out of fossil fuel, or finally realized that it is too precious to burn. That would turn the airliner design requirement upside down. Can you prove such a scenario wrong?

This question doesn't specify whether the solar panels are attached to the plane or not.  If the Boeing plane is restricted to it's own surface area, then the above answers are sufficient to explain NO>
Otherwise, if the solar panels are not attached to the plane, YES. With laser power.  See here >
https://www.nasa.gov/centers/marshall/news/news/releases/2003/03-180.html

Are you sure? It is very difficult to get more than 5 times the solar irradiance to a plane from laser, because you need to cool the photovoltaic cells in the plane.  See: http://www.rand.org/pubs/technical_reports/TR898.html . I was crunching some numbers, and for something equivalent to a current airliner, you want at least one order of magnitude more power density than that. Something like 100 times more than solar power.

YES! it could be done.
I live 10mi from the first nuclear reactor in the world. It is a staggering thought to remember the United States went from the discovery of radioactivity to the nuclear bomb in just 40 years. What seems impossible today is less than $20 at Wall-Mart in 20 years.
I can see where a heavier than air hybrid blimp/flying wing like structure could satisfy all the requirements, A blended body would have a larger surface area than conventional airliner. I expect it to be done within the next 50 years - but will require thinking outside the present convention of what a passenger airplane should look like.

Competes with non-critical freight loads or short haul B737 market (primarily less than 500-600mi.

Gottingen high volume low airspeed airfoil

Boeing concept

I would say yes, but it wouldn't be the type where the solar panels are directly powering the fans. It would require a whole heap of the best and lightest rechargeable batteries and the whole airplane would have to be covered in stick on panels, at best it would decrease the rate of discharge of the batteries. The top speed might only be like 400 kph given you'd be simply using ducted fans rather than turbojet engines but that would still be cool. If it means a big decline in fossil fuel burning I'd personally be happy for flights to take twice as long.


text:
What is this aircraft, and when was it used operationally?

What is this aircraft, when did it serve with the US army, and what was its role?
source: americaloveshorsepower.com

As ymb1 noted, the answer is on the page where you found the image. I'm not quite sure why you asked here...

Looks like a dragonfly!

It is the Grumman OV-1 Mohawk. Incidentally, the Mohawk was the only fixed-wing aircraft ever built specifically for the U.S. Army since the Air Force became a separate service in 1947. According to airspacemag.com:

The OV-1 was designed to meet a joint Marine Corps-Army requirement for a short-takeoff-and-landing battlefield surveillance aircraft. It was intended to operate close to the front lines in support of unit commanders.... The first version, designated OV-1A, was configured to provide a platform for photographic and visual reconnaissance.

Later versions were fitted with Side Looking Airborne Radar (SLAR). It was used by US Army from 1959 to 1996, while the Argentine Army Aviation used it from 1990s to 2015.
It was mainly used for battlefield surveillance and intelligence gathering.

That's an Grumman OV-1 Mohawk.  Used by the United States Army between 1959 and 1996 as a scout spotter and light attack aircraft.


text:
Swing-up canopy not shut in high-speed flight, what would happen?
What would happen to a canopy like that on the Eurofighter Typhoon that swings up if it wasn't shut properly and the plane was going at high speeds, would the canopy blow back open?

In a civilian aircraft, sadly this could happen: http://www.atsb.gov.au/publications/investigation_reports/2014/aair/ao-2014-164/


text:
Lighter than Air Rocket
So I was looking at old airships and a thought crossed my mind.  Would a rocket that benefited from being lighter than air travel faster than standard rockets.  I know the current designs are pretty quick - something like 8 minutes from Earth's surface to orbit.  However, they are extremely expensive to make and dangerous.  I always find lighter than air, aircraft to be fascinating.  I know society seems to think it is an obsolete method for air travel but I would argue the exact opposite.  The old USS Akron aircraft carrier seems like to coolest thing built in the last 100 years and one only need look at the amazing interior of Hindenburg to realize what mankind is missing out on.
As most know, the old airships used propellers for propulsion.  Everybody says how they don't fare well in wind and storms.  It seems like the answer is simply in new propulsion methods.
I imagine the answer could go either way.  If the ship or rocket was small enough than perhaps we would see something really fast, maybe not though.  I think the issue then would be not ripping apart from the g forces.

There are many flawed ideas in your question.  Lighter than air machines don't fare well in winds and storms for the very reason that they are lighter than air.  Changing the propulsion (presumably you are thinking about going faster) will not change the fact that they are lighter than air and will be "pushed around" by the wind.  They will simply fly diagonally faster. Inertia and momentum are the problems, not speed. If your rocket is lighter than air (even assuming that this is constant, which it is not, it must become heavier than air at some point), what payload are you proposing to lift?

The closest studied concept is the "airship to orbit" (ATO) idea: JP Aerospace. The future satellite slowly climbs to low orbit. It's feasible, but so far there are no use case, it's easier to climb with a rocket. However like Cubsats are a new way to access space for small relatively inexpensive applications, or drones are used to deliver pizzas, airship cannot be discarded entirely for future uses.

No.
To orbit you need lots of speed.
To get lots of speed you need lots of mass (propellant)
Lots of mass and lighter than air are antinomic.
Look up this site and space.stackexchange for lots of other negative answers about orbit and blimps.
Ex:
https://space.stackexchange.com/questions/2876/can-we-make-a-space-blimp

I am fairly confident I answered what the OP meant.

That may be true, but you have done this from an arguable assumption: "To go to orbit you need lots of speed" is not correct in theory. Velocity is required only to orbit when the engines are shutdown. You may go to orbit altitude at 1 mm/s if you have engines able to run the required time, or positive buoyancy.

I don't think orbit is considered as a "place" rather than a state. I'm not sure which one of us is being awfully pedantic, but maybe we should wait for the OP's clarifications.

@mins: Going to orbit is not about going high, it is about going sideways really fast.

Yeah, this question seems to be based on the incorrect notion that "orbit" is just a physical location.

I clarified the answer in case someone else don't know the definition of orbit.

@mins There are some misconceptions, indeed. It is safe to assume that  the question is not about those partial orbits that terminate on the surface of Earth, but about common orbits which happen to be regular and repetitive. Some free fall trajectory are orbits, all orbits are free fall trajectories. Following an orbital path through the means of propulsion does not mean to "be in orbit". Proper orbital speed makes all the difference.

There is ONE orbit that is a location though (assuming that the misconception is that we can climb vertically to orbit). Geo-synchronous orbit is the only orbit that requires zero horizontal velocity. So if one can find a way to get to that height slowly one can avoid needing high velocity. But minus a space elevator, the most fuel-efficient way to get there is to accelerate to a transfer orbit and then adjust. Trying to climb slowly at constant velocity requires even more fuel thus would necessitate an even bigger, heavier aircraft.

@slebetman That's untrue; the orbital speed is 11 068 km/h for GEO; while the ground speed at the equator is 1 670km/h. So you don't just need to climb, you also need lots of sideway acceleration.

Hey, thanks to all the responses.  Wasn't really looking for answers on orbits and all that.  It just seems like it would make sense.  I watched a video of a guy propelling a blimp in a similar manner as one rides a bicycle.  It seems like you could push a blimp for propulsion.  I bet it would be incredibly fast.  Who knows though, it just seems like that would be the case.  Airships are different than blimps.  Most people I talk to don't seem to understand that.  However, both become heavier than air at some point.  The whole idea is to get going fast.  Interesting idea nonetheless


text:
Effect of touchdown on angle of attack, tailwheel vs tricycle
I have a theory but I can't find any documented confirmation. Please let me know if my theory seems right:
My theory:
During a regular touchdown, a tricycle gear equipped airplane, since the main wheels are behind the center of gravity, rotates around its transversal axis (nose down), thus reducing the angle of attack. This should reduce the plane tendency to rebound (unless the nosewheel touches the ground).
On a tail-wheel airplane, the effect in reversed, on touchdown the airplane rotates around in transversal axis, thus increasing the angle of attack.
Does that make sense?

Yes, it does make sense.
However, the angle of attack increase of the tailwheel airplane would only be possible if it touches down on the main wheels while there still is much clearance of the tail wheel or skid. Normally, the ground attitude of tailwheel airplanes should be very close to their landing attitude, so all three wheels touch down almost simultaneously.

Yes.  With a tailwheel airplane, if you are trying to make a "wheel landing" (on the main wheels only) rather than a 3-point landing, it is critical that the sink rate be very low at the moment of touchdown, or else the plane will tend to pitch nose-up (tail-down) which will make it bounce back into the air.  A plane with tricycle gear doesn't have this tendency-- it pitches the other way and tends to stay on the ground.  On the other hand, in a tailwheel plane, if you hold it off the ground with aft stick input till it runs out of airspeed and settles to the ground in a three-point attitude, there should be little tendency to bounce even if the sink rate is a little high.

Agreed. Tail wheel aircraft generally have the required angle of attack on touchdown (for a given landing speed) very close to the angle achieved when all three wheels are in contact with the ground. Hence, if the aircraft is landed at too higher speed the tail will be high, and without care, the touchdown can cause the aircraft to rotate around the main wheels with the tail wheel descending and further increasing the angle of attack causing the aircraft to get airborne again or bounce. Even at the correct landing speed, too high a rate of descent on touchdown can have the same effect.

Good point about the higher descent speed, because this will allow for a pitch-up on touch down even when the angle of attack is right for a three-wheel landing. +1

If a taildragger is configured and flown properly, actually the result is the same as for a tri-gear.
If you land 3-point, a "full stall" landing, the ideal is for the tailwheel to make contact just before the mains, so that ground contact has the result of reducing AOA (a tiny amount).  If you contact mains first you are likely to skip or bounce as AOA increases, but you've screwed it up in the first place if that happens.  You could contact with all 3 wheels simultaneously, occasionally, but most of the time it's one or the other and tailwheel first is preferable to mains first.
If you wheel land, on the mains, although the moments are trying to make the plane pitch up at ground contact, the result is the same because with the proper technique, a pitch over is induced by pilot input as part of the landing process.  A proper wheel landing is done by leveling off with the wheels a foot or two above the surface, and then you push the stick (it takes some nerve at first until you get the hang of it).  When ground contact is made, the down elevator input will normally raise the tail a bit more, reducing AOA further, and this also overpowers the pitch up tendency from the CG behind the mains and prevents bouncing.